What Factors Might Have Led to the Emergence of Ebola in West Africa?

This manuscript has been conditionally accepted by PLOS Neglected Tropical Diseases for publication prior to formal review. Following a successful outcome of independent peer review, a revised version will be formally published by PLOS Neglected Tropical Diseases and a link to the final article posted here. Read more here

A PDF of the full text is available: Alexander et al.

What factors might have led to the emergence of Ebola in West Africa?

K.A. Alexander¹, C.E. Sanderson¹, M. Marathe2,3, B.L. Lewis³, C.M. Rivers³, J. Shaman4, J.M. Drake5, E. Lofgren³, V.M. Dato6, M.C. Eisenberg7, and S. Eubank³

1 Department of Fisheries and Wildlife Conservation, Virginia Tech, Blacksburg, Virginia

2 Department of Computer Science, Virginia Tech, Blacksburg, Virginia.

3 Network Dynamics and Simulation Science Laboratory, Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, Virginia.

4 Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, New York

5 Odum School of Ecology, University of Georgia, Athens, Georgia

6 Department of Biomedical Informatics, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania

7 Departments of Epidemiology and Mathematics, University of Michigan, Ann Arbor, Michigan


An Ebola outbreak of unprecedented scope emerged in West Africa in December 2013 and presently continues unabated in the countries of Guinea, Sierra Leone, and Liberia. Ebola is not new to Africa and outbreaks have been confirmed as far back as 1976. The current West African Ebola outbreak is the largest ever recorded and differs dramatically from prior outbreaks in its duration, number of people affected, and geographic extent. The emergence of this deadly disease in West Africa invites many questions, foremost among these: Why now and why in West Africa? Here, we review the sociological, ecological, and environmental drivers that might have influenced the emergence of Ebola in this region of Africa and its spread throughout the region. Containment of the West African Ebola outbreak is the most pressing, immediate need. A comprehensive assessment of the drivers of Ebola emergence and sustained human-to-human transmission is also needed in order to prepare other countries for importation or emergence of this disease.  Such assessment includes identification of country-level protocols and interagency policies for outbreak detection and rapid response, increased understanding of cultural and traditional risk factors within and between nations, delivery of culturally embedded public health education, and regional coordination and collaboration, particularly with governments and health ministries throughout Africa. Public health education is also urgently needed in countries outside of Africa in order to ensure that risk is properly understood and public concerns do not escalate unnecessarily. To prevent future outbreaks, coordinated, multiscale, early warning systems should be developed that make full use of these integrated assessments, partner with local communities in high-risk areas, and provide clearly defined response recommendations specific to the needs of each community.

Competing Interests: The authors have declared that no competing interests exist.

Funding: The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.This work has been partially supported by DTRA CNIMS Contract HDTRA1-11-D-0016-0001. Research reported in this publication was partially supported by the National Institute of General Medical Sciences of the National Institutes of Health under award number 5U01GM070694-11 and U01 GM110748 as well as the RAPIDD program of the Science and Technology Directorate, US Department of Homeland Security and the NLM Pittsburgh Biomedical Informatics Training Grant 5T15 LM007059-28.

Copyright: © 2014 Alexander et al. This is an open-access manuscript distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Continue reading »

Category: Ebola, General | 9 Comments

Mind the Deadly Gaps

Grania Brigden (@TBBrigden) discusses the urgent need to close the gaps in the TB response.

Image Credit: Treatment Action Group

Image Credit: Treatment Action Group

The 45th Union World Conference on Lung Health held in Barcelona last week opened with the Health Ministers of South Africa and India making bold statements and commitments to address and reverse the TB epidemics in their countries. Five other countries also committed to ending TB, resulting in the birth of the Barcelona Declaration on TB.

This political commitment is desperately needed. The recently published WHO Global TB Report 2014 highlighted not only the increasing numbers but also the growing crisis in tackling drug-resistant TB. The reality for those infected with multi-drug resistant TB (MDR-TB) is that they have only a one in eight chance of being identified, correctly diagnosed, started on treatment and cured. This is not acceptable.

Continue reading »

Category: General, MSF, Tuberculosis | Tagged | 2 Comments

EMA’s Release of Regulatory Data: Possible Fall out for Journals and Research Synthesis

On 2 October the European Medicines Agency’s (EMA) published the final version of its policy on prospective release of clinical study reports (CSRs) of trials submitted by sponsors in support of Marketing Authorisation Applications (MAAs).

I have summarized its content and made preliminary comments here

The policy

Image credit: gosheshe, Flickr

Image credit: gosheshe, Flickr

In brief, from 1 January 2015 the proactive policy will join the current reactive policy and allow prospective access to incomplete CSRs at two levels: a “viewer” level of access and a “researcher” level. The former will allow on-screen viewing only with a simple registration procedure, while the latter will require proof of identity but allow download and OCR searches to be carried out on CSRs. Prospective seems to mean two things: after a regulatory decision has been taken, pharma will format and write CSRs for direct web posting, and once you have obtained access credentials, you will not have to ask every time you want a CSR and wait some months (and in some cases be turned down).

Its meaning

The practical importance of the policy hinges on the dawning realization of the difference in accuracy, completeness and trustworthiness of published versions of trials compared to their CSR counterparts. Trials may not be published, some may not even be registered (especially the older ones) posing decades-old problems for readers, users and, from my point of view, evidence synthetisers. Reporting bias (cherry picking) is the broad term which encompasses the scores of different types of bias present in publications. The range from the well-known publication bias to the less known swamping bias (when important information on a trial is missed amidst a sea of other information). CSRs in theory cut through all this by presenting exhaustive structured narratives and results of trials. This is essentially part of what regulators see.

The policy has some as yet unclear legal aspects and sets out equally unclear rules for redaction of CSRs (based on the preservation of commercial interests and protection of participant privacy). It also does not explain why some parts of the CSRs will not be released.

Continue reading »

Category: General | 2 Comments

Social Pathways for Ebola Virus Disease in Rural Sierra Leone, and some Implications for Containment

The below manuscript was initially posted here on October 31st, 2014 following its conditional acceptance by PLOS Neglected Tropical Diseases for publication prior to formal review. The paper has achieved a successful outcome of independent peer review and the final version was formally published on April 17th, 2015. That version is available here

Social pathways for Ebola Virus Disease in rural Sierra Leone, and some implications for containment

Paul Richards¹*, Joseph Amara¹, Mariane C Ferme², Prince Kamara¹, Esther Mokuwa¹, Amara Idara Sheriff¹, Roland Suluku¹, and Maarten Voors³

1 Njala University, Sierra Leone

2 University of California, Berkeley, United States of America

3 Wageningen University, The Netherlands

*Corresponding author: paul.richards@wur.nl.


The current outbreak of Ebola Virus Disease in Upper West Africa is the largest ever recorded.  Molecular evidence suggests spread has been almost exclusively through human-to-human contact.  Social factors are thus clearly important to understand the epidemic and ways in which it might be stopped, but these factors have so far been little analyzed.  The present paper focuses on Sierra Leone, and provides data on the least understood part of the epidemic – the largely undocumented spread of Ebola in rural areas.  Various forms of social networking in rural communities and their relevance for understanding pathways of transmission are described.  Particular attention is paid to the relationship between marriage, funerals and land tenure.  Funerals are known to be a high-risk factor for infection.  It is suggested that more than a shift in awareness of risks will be needed to change local patterns of behavior, especially in regard to funerals, since these are central to the consolidation of community ties.  A concluding discussion relates the information presented to plans for halting the disease.  Local consultation and access are seen as major challenges to be addressed.

Competing Interests: The authors have declared that no competing interests exist.

Funding: International Initiative for Impact Evaluation (3ie) through the Global Development Network (GDN) grant #TW1.1042 to MV and PR, http://www.3ieimpact.org/en/  UK Economic and Social Research Council (ESRC) grant # ES/J017620/1 to MV and PR, http://www.esrc.ac.uk/ National Science Foundation, grant # 1430959 to MF, http://www.nsf.gov FAO and Irish Aid funds to EM and PR, http://www.fao.org/home/en/  https://www.irishaid.ie/The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Copyright: © 2014 Richards et al. This is an open-access manuscript distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Beyond zoonosis

The present outbreak of Ebola Virus Disease (EVD) in Upper West Africa is the worst ever recorded.  Currently (late September 2014) it has a case doubling rate of three weeks, and shows no signs of coming under control.  The international community is alarmed, and resources are being rushed to the region to try and stem further spread.  The epidemic is an outbreak of the Zaire strain of the virus, previously associated with death rates of up to 90 per cent.  Death rates in the Upper West African outbreak average 70 percent (WHO 2014)

The epidemic has been traced to a single index case – the infection of a 2 year-old boy in the village of Meliandou, in the Republic of Guinea (Baize et al 2014, Bausch and Schwarz 2014). Previous outbreaks of the disease have occurred in remote forest edge communities, and have been associated with hunting and eating of bush meat.  This scenario appears not to be appropriate for the present epidemic.  Human-to-human transmission appears to be the main if not sole source of infection.

In this paper we offer some data and observations relating to the Sierra Leone epidemic (Figure 1).  If human-to-human contact is the main mode of transmission attention needs to be paid to underlying social factors.  The paper is divided into three sections.  A case-study based scenario for the spread of EVD in Sierra Leone is described (based on interviews and direct observation by two Njala-based authors of the present paper, RS and JA), and proposes greater attention should be paid to rural buffers for the disease.  We then identify and explain the role of processes related to marriage, land and burials significant for spread of the disease.  A concluding discussion considers what assistance might be necessary if rural communities are to reduce current transmission rates.

Continue reading »

Category: Ebola, General | 10 Comments

A Rapid Response to Ebola

November 11th 2014 Update: Two manuscripts have now been posted to Speaking of Medicine and can be viewed here:

Social Pathways for Ebola Virus Disease in Rural Sierra Leone, and some Implications for Containment

What factors might have led to the emergence of Ebola in West Africa?

Original Post:

The ability to rapidly disseminate the findings of primary research as well as informed scientific assessment and opinion is critical in the face of public health emergencies such as the present outbreak of the Ebola virus.  At PLOS, primary research findings can be rapidly and effectively distributed through PLOS Currents: Outbreaks. The unmet need to provide expert commentary and insightful opinion on Ebola as rapidly has led PLOS Neglected Tropical Diseases to carefully select expert opinion, social science assessment, or topic reviews for public posting on Speaking of Medicine before formal and rigorous peer review.

The authors of manuscripts identified by the Editors as suitable are offered the opportunity to post their text with the understanding that, because of its quality and likely favorable review, is conditionally accepted for publication in the journal.  Authors are required to provide confirmation of authorship as well as financial disclosure and competing interest statements, which will be posted along with the text.

The Editors of PLOS Neglected Tropical Diseases are excited to provide a platform to make available much needed information publicly, openly, responsibly, and as quickly as possible.

For questions or further information, please contact PLOS NTDs Publications Manager Jeri Marie Wright at jwright@plos.org

Category: Ebola, General | 2 Comments

Researchers Follow the Path of HIV and Prevention Interventions

Charlene Dezzutti from the University of Pittsburgh and the Magee-Womens Research Institute explains how HIV researchers are incorporating biomarkers and preclinical testing – featured in the PLOS Collection Advances in HIV Mucosal Immunology: Challenges and Opportunities – in their pursuit of an effective HIV preventative such as a topical microbicide gel or an oral pill containing anti-retroviral drugs or a vaccine.

Biomarkers are biological substances that mark the presence of a disease or condition in a person. For instance, cholesterol level is a biomarker for heart disease and CD4+ T cell counts or plasma HIV RNA levels are biomarkers for HIV disease progression. Biomarkers are important because they allow physicians to track an individual patient’s condition during treatment to better predict and improve health outcomes.

Image Credit: Artistic rendition of immune cells and potential HIV targets in the rectal mucosal. Yang, Ochoa, Preza & Anton, 2014

Image Credit: Artistic rendition of immune cells and potential HIV targets in the rectal mucosal. Yang, Ochoa, Preza & Anton, 2014

Likewise, biomarkers of product safety and efficacy would provide a tremendous benefit to the HIV prevention field because they would help identify preventatives that are safe and effective. Since newly developed experimental products cannot be tested in humans, models that accurately predict how humans would react – called “preclinical models” – are used. Because HIV in adults is usually transmitted sexually, with the exception of intravenous drug users, researchers have been targeting the tissues and routes that first encounter the virus to better understand the dynamic host-pathogen interaction.  Researchers are now working to develop and test animal and ex vivo tissue culture models to try and predict how these new HIV prevention products will work in people. The latest models use human mucosal tissue and secretions as well as non-human primates to mimic as closely as possible human exposures and potential responses.
Continue reading »

Category: General | 1 Comment

Urbanisation Up Close

Jocalyn Clark @jocalynclark discusses the urbanisation of the world’s population and its impact on global health.

Image credit: joiseyshowaa, Flickr

Image credit: joiseyshowaa, Flickr

Undeniably the world is urbanising. By 2050, according to the UN, the world’s urban population will almost double from its 2007 size of 3.3 billion to 6.3 billion people. The developing world will have more urban than rural dwellers by 2030. In terms of health, urbanisation gives rise to new threats and needs when delivering services.

Migration to cities usually means job prospects, educational opportunities, access to health care, and financial security for families. It can bring relief from conflict or land degradation. But it also brings problems associated with inadequate housing, overcrowding, air pollution, and road traffic. Both infectious (pneumonia, tuberculosis) and non-communicable (cardiovascular, diabetes) diseases increase with urbanisation.

I thought I knew big cities – the opportunities and the inconveniences – having lived in Toronto and London and travelled to many more across the developed and developing worlds. Then I moved to Dhaka, one of the world’s fastest growing cities (it grew an astonishing 45% between 2000-2010). Already 14 million people and densely crowded, by 2025 the UN predicts Dhaka will be home to more than 20 million people — larger than Mexico City, Beijing or Shanghai. Without the infrastructure, planning, or governance of those wealthier cities, Dhaka is like a poor cousin of mass urbanisation. Or, as a commentator recently said, it’s the ‘mega city of the poor.’

Continue reading »

Category: Global Health | 3 Comments

Ebola has Taught us a Crucial Lesson about our Views of “Irrational” Health Behaviors

Sara Gorman compares “irrational” reactions to the Ebola outbreak by Americans and West Africans.

As Ebola rears its ugly head in the U.S., there has been a lot of discussion about how afraid we really should be. While health officials have remained relatively calm, insisting in a tense congressional hearing that there is no need to panic, some members of the American public have gone in the opposite direction, proclaiming a state of emergency on social media channels such as Twitter and Facebook. Donald Trump has been an especially noisy voice on the topic on Twitter, demanding that Obama stop all flights to and from West Africa and proclaiming that Ebola is actually much more contagious than the CDC says it is. At the end of September, with the announcement of the first suspected case of Ebola in the U.S., Trump expressed panic on Twitter, writing:

trump 1

trump 2

Trump’s comments suggest not only a distrust of health authorities but also a kind of hysteria, with the use of the word “plague,” that is reminiscent of the infectious disease panic seen in many other outbreaks in American history, including SARS in 2003 and bubonic plague in 1924, the latter an outbreak that famously led to the frantic firing of thousands of Latino workers and destruction of homes in low-income Latino neighborhoods because they were seen as the “source” of the disease.

Continue reading »

Category: Ebola, General | 7 Comments

The Price of Joining the ‘Middle Income Country’ Club: Reduced Access to Medical Innovation

On November 5, 2014, the WHO, WIPO and WTO will hold a joint symposium to discuss innovation and access to medical technologies in middle-income countries. In this post, Judit Rius Sanjuan and Rohit Malpani of Médecins Sans Frontières discuss the barriers to health care access for poor people in middle-income countries.

When people think about medical humanitarian aid, the usual association is with war zones and natural disasters, and the assumption is that the most critical medical needs are concentrated in the world’s poorest countries. That’s mostly right, but not entirely: while the needs in low-income countries remain huge, large—and growing—populations excluded from access to health care now live in countries classified as Middle Income (MIC). This shift presents enormous challenges, particularly in accessing new life-saving drugs and vaccines for diseases that take a disproportionately high toll on poor, marginalized populations.

For us at Médecins Sans Frontières (MSF), an organization providing emergency medical aid to people in acute need, the bulk of our resources are placed in countries classified as low-income economies. But over half the countries where we now have programs are classified as middle- or high-income economies. These programs range from short-term emergency responses, for example after last year’s Typhoon Haiyan in the Philippines, to aid for ongoing refugee emergencies in Iraq, Jordan, and Lebanon, to treatment programs for chronic and neglected diseases in India and South Africa.


Image Credit: Images_of_Money, Flickr

Today, more than 100 diverse economies are classified as MIC.  They are home to about 5 billion of the world’s 7.1 billion people, including more than three-quarters of the poorest people living on less than $2 per day, largely due to enormous and rising levels of inequality.

Yet the rising economic indicators that land a country in the MIC club in turn often exclude those countries from accessing the lowest prices for medicines and vaccines, due to tiered pricing and other market segmentation strategies employed by pharmaceutical companies, and increasingly by donors, governments and international organizations. In many MICs, health care costs are primarily paid out of pocket, so it follows that many poor and marginalized people have little or no access to care.
Continue reading »

Category: General, MSF | Tagged | 3 Comments

I’ve Got a (lot of) Little (check)lists

PLOS Medicine Editorial Director, Virginia Barbour, reflects on the publication of the CONSORT and PRISMA guidelines and reminds us of the importance of checklists to medical publishing.

Image credit: Oliver Tacke, Flickr.

Image credit: Oliver Tacke, Flickr.

Gilbert and Sullivan’s Lord High Executioner has, sadly given lists a bad name. Rather than tools of revenge, lists in healthcare, however, have the power to do much good. Atul Gawande’s book on lists has explained why they should be core to medical practice. I’d argue that in medical publishing too they are critical.

When Robert Boyle, one of the founders of the UK’s Royal Society, wrote the Spring of the Air he was probably the first to write in such a way that allowed other men (it was only men then of course) to repeat and test his findings.  In this way he was in turn one of the first to legitimize research by making it reproducible.

More than 300 years later we have a fully reproducible literature with everything fully reported, right? Wrong. There is a current crisis of confidence in research, with increasing and appropriate concern that many results, especially the most dramatic, often cannot be trusted. Contributing fundamentally  (but not exclusively, obviously) to this problem is that whole swathes of the medical and scientific literature are not described in sufficient detail that anyone else can even test. In medicine this crisis literally is life threatening; patients given treatments as a result of inadequately described studies may at best be treated sub-optimally, at worst harmed or killed.

However, in one important corner of the research endeavor a group of individuals, have, for many years now, been making a determined effort to change this poor reporting and PLOS Medicine is proud to have played its part in it. The CONSORT reporting guidelines for clinical trials and the PRISMA guidelines for Systematic Reviews and Meta-Analyses are, I’d argue two of the most important papers the journal has ever published. The premise behind both of these documents, and the checklists in them and the many other guidelines that we and other PLOS journals have published is very simple: tell us what you did so others can test it.

Continue reading »

Category: 10th Anniversary | 2 Comments